Neutral tubing for panelboards



March 18, 1969 B STANCJL NEUTRAL TUBING FOR PANELBOARDS Filed Oct. 24, 1966 United States Patent Oliice 3,434,102 Patented Mar. 18, 1969 3 Claims This invention relates generally to conductor terminal blocks, and, more particularly, to a method of assembling a conductor terminal block in a simplified and etlicient manner.

Conductor terminal blocks such as described herein serve as a convenient means to both physically and electrically secure conductors to each other, to ground or common terminals, or to both, as may be desired. Such blocks find common usage in fusible and circuit breaker panel boards to accommodate neutral wires. A typical terminal block will usually comprise a base structure provided with openings for the insertion of conductors and -a series of terminal screws each mounted above a conductor passageway so as to enable electrical and physical contact to be secured `by the tightening of a terminal screw onto its respective conductor.

Present termin-al block manufacturing methods have inherent diiliculties. Invariably t'hese methods involve drilling a solid metallic base material from two directions for each terminal position. Should the base be extruded rectangular tubing, a punching operation would be required from three directions.

One of the resulting holes must then be tapped to accommodate the terminal screw, or a self threading screw inserted into the hole. These drilling and tapping operations must be carefully done to insure proper orthogonal alignment between each terminal screw and its associated underlying conductor passageway. Waste material resulting from the tapping `operation must be carefully removed so that no obstacle will impede the terminal screw or 'block the conductor passageway. The painstaking nature of this operation is costly, time consuming, and inel'licient.

The entire unit consists of three basic parts, namely:

(1) A copper base which can be fabricated from flat copper stock by punching and forming to create a helically ribbed element.

A steel cap piece which can be punched from fiat stoc (3) A plurality of termin-al screws. The method of 'assembly is as follows:

(a) The terminal screws are placed in the clearance holes of the flat steel cap piece. This will properly align the terminal screws for insertion into the formed copper base.

(b) With the terminal screws and cap piece in place, the steel cap is formed over and crimped to the formed copper base. This operation secures the steel cap to the copper base and also presses threads into the opposing walls of the copper base by using the terminal screws as the thread forming means. Thus, the steel cap will prevent the copper base from opening up when pressure is applied to the terminal screws.

It is, therefore, a primary object of the invention to provide `a method of fabricating and assembling a conductor terminal block wherein all tapping operations are eliminated. To this end, the terminal screw thread is formed by supporting a helically ribbed element between :a pair of opposing surfaces, and applying lateral pressure to said pair `of opposing surfaces so as to cause an impression of said helically ribbed element to be tarnferred to the inner surface of said pair of opposing surfaces.

It is a further object of the invention to fabricate a complete terminal block in a single forming operation without the need of subsequent insertion of the terminal screws.

It is a still further object of the invention to provide a method of fabricating and assembling terminal blocks such that each terminal screw will be orthogonally aligned with its associated underlying conductor passage.

Further objects and advantages of the invention will become apparent when described in connection with the laccompanying drawings, in which:

FIGURE 1 is a perspective view of the individual units prior to assembly.

FIGURE 2 is a perspective view of the assembled unit.

Referring to the drawings, elements 10i represent a series of terminal screws, or any type of helically ribbed element, to be set within the terminal block. As illustrated the said terminal screws 10 may be of the simple cap screw variety with a slotted top 12 to provide for convenient linear adjustment, and a helically ribbed or threaded cylindrical shaft 11.

A capping piece 20 is provided with a series of properly spaced apertures 21 of sufcient diameter so as to pass the terminal screws 10. The capping piece 20 may be a at prepunched sheet material, preferably of steel, with an extended width 22 which will overlap terminal base unit 30 for reasons that will subsequently become apparent.

Terminal base 30 is a preformed, prepunched, malleable, copper shell, substantially U-shaped, which may be fabricated from ilat copper stock. The side walls 31 are `formed in an opposed corrugated effect 32 which form a series of circular open-ended loop openings 32, the inner diameters thereof being slightly greater than the shaft 11 of each of the terminal screws 10. A plurality of prepunched orifices 33 are provided on each side of sidewalls 31 to allow for passage of conductor-s therein. Depressions 34 are provided toward the innermost portions of the sidewall corrugations 32 for reasons which will subsequently become apparent.

The method of assembly is accomplished in the lfollowing manner:

The terminal screws 10 are each inserted into their respective apertures 21 on capping piece 20 and then into the opposed rounded openings 32 in terminal base 30 along the axis lines 23. The spacing of apertures 21 on capping piece 20 insures proper orthogonal alignment between the terminal screws 10 and the axes 35 of the formed openings 33 of terminal base 30. Once assembled, the entire unit is subject to a lateral pressure by any appropriate mechanism (not shown) which will cause the overlying lip 24 of the capping piece 20 to fold over the top edges of sidewalls 31 and crimp the folded edge to conform to the depressions 34. The completed unit is shown in FIGURE 2. The crimped indentations in folded lip Z4 are designated generally as 25. The folding pressure `described above also serves to press the threaded shaft 11 of the terminal screws 10 into the inner walls 31 of terminal base unit 30, thereby eliminating the need for tapping operations. Once in position, capping piece 20 serves to maintain the terminal base unit 30 in rigid position, preventing it from opening when pressure is applied to a terminal screw or screws 10.

The Iabove described unit was designed to accommodate neutral wires ranging from 14 to 4 (American Wire Gage) for use in fusible and circuit breaker panelbo'ards. This is stated by way of example only and the invention is by no means limited by such design or application, or by the embodiment of the invention described above.

Various modifications withinthe spirit of the inventionv may occur to those skilledin the art and it is intended that no limitations be placed on the invention except as deiined by the scope of the appended claims.'

The embodiments of the invention in which an eX- clusive privilege or property is claimed are defined as follows:

1. A terminal block for conductors comprising a substantially U-shaped terminal base having a pair of upright opposing corrugated surfaces arranged to form a series of open ended loops, each of said pair of upright opposing corrugated surfaces further formed to accommodate a series of conductors inserted in conductor passageways therein parallel to one another but orthogonal with respect to the long axis of said terminal base, capping means xedly mounted along the upper length of said terminal base thereby rigidly maintaining the shape of said terminal base, said capping means supporting a series of downwardly extending helically ribbed cylindrical shafts mounted thereon at intervals fixed such that said helically ribbed cylindrical shafts are each axially disposed orthogonally to each axis formed by said conductor passageways and coincident with the longitudinal axis formed by each of said open ended loopsfeach of said pair of up- References Cited UNITED STATES PATENTS 2,905,923 9/1959 Hammerly 339-198 2,907,977 10/ 1959 Daley. 2,943,294 6/ 1960 Norden. 3,075,164 1/1963 Hurnpage et al. 3,144,293 8/1964 Desmidt 339-244 MARVIN A. CHAMPION, Primary Examiner.

PERRY TEITELBAUM, Assistant Examiner.

y i Us. C1, X.R. 29 63o; 339-198, 244, 272 

1. A TERMINAL BLOCK FOR CONDUCTORS COMPRISING A SUBSTANTIALLY U-SHAPED TERMINAL BASE HAVING A PAIR OF UPRIGHT OPPOSITE CORRUGATED SURFACES ARRANGED TO FORM A SERIES OF OPEN ENDED LOOPS, EACH OF SAID PAIR OF UPRIGHT OPPOSING CORRUGATED SURFACES FURTHER FORMED TO ACCOMMODATE A SERIES OF CONDUCTORS INSERTED IN CONDUCTOR PASSAGEWAYS THEREIN PARALLEL TO ONE ANOTHER BUT ORTHOGONAL WITH RESPECT TO THE LONG AXIS OF SAID TERMINAL BASE, CAPPING MEANS FIXEDLY MOUNTED ALONG THE UPPER LENGTH OF SAID TERMINAL BASE THEREBY RIGIDLY MAINTAINING THE SHAPE OF SAID TERMINAL BASE, SAID CAPPING MEANS SUPPORTING A SERIES OF DOWNWARDLY EXTENDING HELICALLY RIBBED CYLINDRICAL SHAFTS MOUNTED THEREON AT INTERVALS FIXED SUCH THAT THE SAID HELICALLY RIBBED CYLINDRICAL SHAFTS ARE EACH AXIALLY DISPOSED ORTHOGONALLY TO EACH AXIS FORMED BY SAID CONDUCTOR PASSAGEWAYS AND COINCIDENT WITH THE LONGITUDINAL AXIS FORMED BY EACH OF SAID OPEN ENDED LOOPS, EACH OF SAID PAIR OF UPRIGHT OPPOSING CORRUGATED SURFACES BEING HELICALLY RIBBED TO ENGAGE ONE OF SAID HELICALLY RIBBED CYLINDRICAL SHAFTS THEREBETWEEN. 